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G. STOHN MECHANICAL ROASTING FURNACE Aug. 26 1924. 1,506,266

Filed Jan. 26 1921 Fig.1;

Patented Aug. 26, 1924.

PATENT OFFICE.

GEOBG STO'HN, OF STOLBERG, GERMANY.

MECHANICAL ROASTING FURNACE.

Application filed January 26, 1921.

To all whom it may concern:

Be it known that I, Gnono SToHN, engineer, citizen of the German Republic, and residing at Stolberg, Bheinland, Germany, have invented certain new and useful Improvements in a Mechanical Roasting Furnace, of which the following is a statement.

In order to reduce the cost of working mechanical ore roasting furnaces and in order to attain a satisfactory working capacity, various devices have been proposed which enable those parts which are most subjected to wear, namely the rabble arms and the rabble arm teeth to be exchanged. It has for instance been proposed to provide the rabble arms with dove-tailed slots into which the individual rabble arm teeth are removably inserted.

The employment of such devices in connection with roasting furnaces having metal rabble arms does not present any difficulty, and it is quite easy in these cases to exchange the worn out part of the rabble arm teeth, during the operation.

The conditions are quite different in the case of roasting furnaces, for instance the Spirlet furnace, in which the rabble stones are each made as a whole of fire-proof material, and are inserted into the brick-work of the furnace, or into the roasting arches or hearth-plates.

With such roasting furnaces the exchange of worn out parts necessitates the furnace to be put out of action for a comparatively long time, and amounts to premature and considerable renovation of a large part of the fire-proof brick-work which but for the insertion of a new rabblestone, could still have been used for a long time.

This is also the reason why a renovation of a furnace is not readily decided upon; as a rule the furnace is allowed to deteriorate, and work less and less efhciently and the repairing is undertaken only as an ultimate resort.

It is the object of the present invention to avoid these drawbacks. For this purpose the individual rabble-stones are removably inserted into the brick-work of the furnace and can therefore be exchanged without removing the brick-work or partly destroying same, and without stopping the furnace Serial No. 440,232.

for a considerable time. The rabble-stone suitably consists of several, preferably two parts, in which case the upper part is located in the brick-work or in the roasting crown or arch, whilst the lower part of the rabble-stone which is particularly exposed to wear is removably secured to the upper part; the lower part may be easily exchanged during the operation.

In contradistinction to the known roasting furnaces in which the individual rabble teeth are removably fixed in the stirrer, the present invention provides a rabble stone which may as an independent Whole be removably inserted into the brick-work of the furnace.

The improved rabble-stone is shown by way of example in the accompanying drawings, in which Fig. 1 is a section through the hearth-plate and the upper part of an inserted rabble-stone, Figs. 2 and 3 are constructional forms of the removable connection of the lower and upper parts of the rabble-stone.

The upper part A of the rabble-stone is of inverted frusto-conical form. It is inserted from above into the arch B, and cannot drop downwardly out of the arch opening which it fills completely, but may at the same time be easily removed therefrom. In order to prevent removal of the stone in the upward direction, wedges C are inserted laterally after the stone has been inserted.

The removable connection of the lower part of the rabble-stone with the upper part, may be attained in'various ways.

According to Fig. 2, the lower part B may be inserted from the side into the part A by the provision of a. dovetailed groove D in one of said parts and of a corresponding tongue C on the other and may then be fixed in position by a wedge F.

According to Fig. 3 two pins G having a dove-tailed section project from the under surface of the part A, the part A having corresponding slots H, I. The part B is fixed to the part A by a suitable turning movement.

Claims:

1. A removable conically-shaped rabble stone consisting of two parts, the upper part being arranged to be inserted into the rotary hearth plate of a mechanical roasting furnace, and the lower part being exchangeably secured to the upper part.

2. A removable conically-shaped rabble 5 stone consisting oftwo parts,' the upper part being arranged to be inserted into the rotary hearth plate of a mechanical roastmg wedges, to prevent the removal of the stone furnace and having laterally inserted in the upward direction, and the lower part 10 being exchangeably secured to the upper art. p In testimony whereof I ailix my signature in presence of two witnesses.

GEORG STOHN. Witnesses v C; SoHLUNBAoH, M. HAUSDING. 

